This invention relates to tobacco feeders, and, more particularly, to slat conveyors for use in a tobacco feeder.
Tobacco feeder machines are utilized to elevate tobacco in bulk quantities from a low level input or dump station to a higher level discharge station at an accurate volumetric rate. Bulk tobacco feeders generally include a lower or hopper conveyor at the input station onto which the tobacco is loaded for movement along a substantially horizontal run to an inclined feed conveyor. The feed conveyor moves the tobacco from a pick-up station at the end of the hopper conveyor to an elevated position for further processing. In order to limit the overall length of the tobacco feeder, the feed conveyor follows a steeply inclined run from the hopper conveyor to the discharge station at the upper level.
The conveying surfaces of both the feed and hopper conveyors of prior art bulk tobacco feeders are conventionally a rubber or rubberized belt. The continuous, rubberized surface of the belt frictionally engages the tobacco to help move it along the conveyor runs, and the belt also prevents smaller particles and fines of the tobacco from dropping out of the feeder machine.
One problem with tobacco feeders employing a rubberized belt is that the belts have a useful life of only two to eight years, depending on the extent of use. The remaining elements of the tobacco feeders last much longer, and therefore the rubberized belts must be replaced many times over the life of the feeder creating maintenance problems, interruptions of production for belt replacement and additional expense. Moreover, the rubberized belts may become contaminated with bacteria from the tobacco, and it has proven difficult to thoroughly wash down the belts after use.
Slat conveyors, which employ a plurality of adjoining, transverse metal slats to form a conveying surface, have been proposed as a replacement for rubber belts in tobacco feeders as discussed, for example, in U.S. Pat. No. 3,259,228 to Wilding. The advantage of using metal slats instead of a rubberized belt is that the slats last about as long as the feeder machine and need not be replaced. However, other problems are created. The metal slats form a smooth conveying surface along which the bulk tobacco can slide as it moves up the steeply inclined run of the feed conveyor of a tobacco feeder. In addition, individual adjoining slats of prior art slat conveyors often do not tightly abut one another, creating gaps therebetween. Fines and other small particles of tobacco placed on such conveyors can either pass through the gaps between adjoining slats or accumulate therein requiring a great deal of cleaning to maintain the surrounding equipment clear of particles.
Also, where slats are of substantial length, such as 6 or 8 feet or more, the tobacco load tends to bend them out of shape.